Application of CNTs/LaVO4 on photocatalytic degradation of methylene blue in different contact modes

In this work, carbon nanotubes/lanthanum vanadate (CNTs/LaVO
4
) nanocomposite performance was evaluated for photocatalytic degradation of methylene blue (MB). The optimization of operating parameters (pH, catalyst dose and initial MB concentration) was performed using response surface methodology (RSM). The optimum values of pH, initial MB concentration and catalyst dose were 6.43, 5.0 mg/L and 0.19 g/L, respectively. A model with R
²
(99.17
^%
) was developed to relate the removal efficiency with the operating parameters. The effects of scavengers reveal that holes and superoxide radicals were the major reactive species in the photocatalytic reaction. The degradation efficiencies in five repetitive cycles were 96%, 94%, 92.3%, 90.5% and 89% using 0.1% CNTs/LaVO
4
, while they were 91%, 88%, 83.3%, 79% and 77% using bare LaVo4.The intermediates generated during the treatment process were identified and the degradation pathway was suggested.